A new fluorescent smart unit (BNAP) based on bisnaphthalimide was designed and synthesized, in which two naphthalimide segments were conjugated through a twisted single bond at the 4-site. With the dual naphthalimide planes, BNAP can act as a double-channel rotor, which can output the shorter emission in the twisted state and the longer emission in the planar state. Because of the restriction of intramolecular rotation (RIR) effects, BNAP showed strong emission character in high viscosity circumstances. The longer and moderate emission in aggregates is attributed to the synergetic effects of RIR and intramolecular planarization. As a molecular rotor with dramatic changes in both emission wavelength and intensity, BNAP could be developed for the rapid detection of viscosity. The probe generates a logarithmic response to the viscosity of a glycerol/water system with different ratios. Furthermore, the probe exhibits high sensitivity to viscosity-related temperature variations. This property is very important because temperature always changes the surrounding viscosity in many biological systems and mechanical systems.

Carbon materials usually exhibit a low capacity, short cycle life and poor rate performance as anode materials for lithium ion batteries (LIBs) and sodium ion batteries (SIBs). It remains a great challenge to explore carbon materials for ultrafast lithium and sodium storage with both a high capacity and a long cycling stability. Herein, we report the fabrication of nitrogen (N)/oxygen (O) dual dopant hollow porous carbon nanocapsules that show a state-of-the-art electrochemical performance. If used as anodes for LIBs, at an ultrahigh current density of 30 A g⁻¹, the carbon nanocapsules can be cycled up to 11 000 cycles with a considerable capacity retention of ∼310 mA h g⁻¹. For sodium storage, they also demonstrate an ultrastable cycling performance with a reversible capacity of ∼150 mA h g⁻¹ after 10 000 cycles at a high current density of 5 A g⁻¹. The outstanding electrochemical performance can be ascribed to the synergistic effects from heteroatom doping and the unique sealed porous hollow characteristics of the nanocapsules. Theoretical calculations suggest that the sealed capsule structure leads to a excellent mechanical stability, which can tolerate fast lithium/sodium intercalation and extraction at ultrahigh current densities.